Hybrid catalyst convective preheating system

Abstract

A catalyst heating system includes a monitoring module, a mode selection module and an electrically heated catalyst (EHC) control module. The monitoring module monitors at least one of (i) a first temperature of a non-EHC of a catalyst assembly in an exhaust system of an engine and (ii) an active catalyst volume of the catalyst assembly. The mode selection module is configured to select an EHC heating mode and generate a mode signal based on the at least one of the first temperature and the active catalyst volume. The EHC control module controls current to an EHC of the catalyst assembly based on the mode signal.

What is claimed is: 
     
       1. A catalyst heating system comprising:
 a first electronic circuit configured to monitor at least one of (i) a first temperature of a non-electrically heated catalyst (EHC) of a catalyst assembly in an exhaust system of an engine and (ii) an active catalyst volume of the catalyst assembly; 
 a second electronic circuit configured to select an EHC heating mode and generate a mode signal based on the at least one of the first temperature and the active catalyst volume; 
 a third electronic circuit configured to control current to an EHC of the catalyst assembly based on the mode signal; 
 a fourth electronic circuit configured to monitor a second temperature of the EHC; and 
 a fifth electronic circuit configured to compare the second temperature to an EHC convection temperature and generate a first comparison signal, 
 wherein the EHC convection temperature is a predetermined amount greater than a predetermined non-EHC convection temperature, 
 wherein the second electronic circuit is configured to, while current is supplied to the EHC, select an air pumping mode to prevent the first temperature from exceeding the predetermined non-EHC convection temperature, and 
 wherein the air pumping mode includes at least one of (i) rotating a crankshaft of the engine while the engine is deactivated, and (ii) activating an air pump. 
 
     
     
       2. The catalyst heating system of  claim 1 , further comprising a sixth electronic circuit, wherein:
 the second electronic circuit is configured to select an engine speed maintaining mode and the air pumping mode and generate the mode signal based on the second temperature; 
 the sixth electronic circuit is configured to initiate at least one pumping action to pump air into an inlet of the catalyst assembly during the air pumping mode; and 
 the at least one pumping action includes the at least one of (i) the rotating of the crankshaft of the engine when the engine is deactivated, and (ii) the activating of the air pump. 
 
     
     
       3. The catalyst heating system of  claim 2 , wherein spark and fuel of the engine are disabled when the engine is deactivated. 
     
     
       4. The catalyst heating system of  claim 2 , further comprising a seventh electronic circuit configured to compare the active catalyst volume to a predetermined volume and generate a second comparison signal,
 wherein the second electronic circuit is configured to select the air pumping mode when the second comparison signal indicates that the active catalyst volume is less than the predetermined volume. 
 
     
     
       5. The catalyst heating system of  claim 2 , further comprising a seventh electronic circuit configured to compare the first temperature to a catalyst light off temperature and generate a second comparison signal,
 wherein the second electronic circuit is configured to select the air pumping mode when the second comparison signal indicates that the first temperature is less than the light off temperature. 
 
     
     
       6. The catalyst heating system of  claim 5 , wherein:
 the EHC convection temperature is a maximum EHC convection temperature; 
 the second electronic circuit is configured to select the air pumping mode when the second comparison signal indicates that the second temperature is greater than the maximum EHC convection temperature; and 
 the second electronic circuit is configured to select the engine speed maintaining mode when the second comparison signal indicates that the second temperature is less than or equal to the maximum EHC convection temperature. 
 
     
     
       7. The catalyst heating system of  claim 6 , further comprising an eighth electronic circuit configured to compare the second temperature to a minimum EHC convection temperature and generate a third comparison signal,
 wherein the second electronic circuit is configured to select the engine speed maintaining mode when the third comparison signal indicates that the second temperature is less than the minimum EHC convection temperature, and 
 wherein the second electronic circuit is configured to select the air pumping mode when the third comparison signal indicates that the second temperature is greater than or equal to the minimum EHC convection temperature. 
 
     
     
       8. The catalyst heating system of  claim 2 , further comprising the catalyst assembly, wherein:
 the catalyst assembly comprises
 the non-EHC, and 
 the EHC upstream from the non-EHC; and 
 
 the third electronic circuit is configured to transfer heat from the EHC to the non-EHC during the air pumping mode. 
 
     
     
       9. The catalyst heating system of  claim 2 , wherein:
 the third electronic circuit is configured to activate the air pump to pump ambient air into the exhaust system upstream from the catalyst assembly during the air pumping mode; 
 the second electronic circuit is configured to select the air pumping mode when an engine speed is less than a predetermined speed; and 
 the third electronic circuit is configured to control operation of an electric motor to
 prevent the crankshaft from rotating during the engine speed maintaining mode, and 
 permit the crankshaft to rotate during the air pumping mode. 
 
 
     
     
       10. The catalyst heat system of  claim 1 , wherein the first electronic circuit is configured to estimate the at least one of the first temperature and the active catalyst volume based on an engine speed, a flow rate, and at least one of a current and voltage of the EHC. 
     
     
       11. A catalyst heating system comprising:
 a first electronic circuit configured to monitor a first temperature of a non-electrically heated catalyst (EHC) of a catalyst assembly in an exhaust system of an engine; 
 a second electronic circuit configured to monitor a second temperature of an EHC of the catalyst assembly; 
 a third electronic circuit configured to select an engine speed maintaining mode and an air pumping mode and generate a mode signal based on the first temperature and the second temperature; 
 a fourth electronic circuit configured to initiate at least one pumping action to pump air into an inlet of the catalyst assembly during the air pumping mode, 
 wherein the at least one pumping action includes (i) rotating a crankshaft of the engine when the engine is deactivated and (ii) activating an air pump; and 
 a fifth electronic circuit configured to compare the second temperature to a maximum EHC convection temperature and generate a first comparison signal, 
 wherein the third electronic circuit is configured to select the air pumping mode if the first comparison signal indicates the second temperature being greater than the maximum EHC convection temperature, and 
 wherein the third electronic circuit is configured to select the engine speed maintaining mode if the first comparison signal indicates the second temperature being less than or equal to the maximum EHC convection temperature. 
 
     
     
       12. The catalyst heating system of  claim 11 , further comprising a sixth electronic circuit configured to compare the first temperature to a catalyst light off temperature and generate a second comparison signal,
 wherein the third electronic circuit is configured to select the air pumping mode when the first comparison signal indicates that the first temperature is less than the light off temperature. 
 
     
     
       13. The catalyst heating system of  claim 12 , further comprising a seventh electronic circuit configured to compare the second temperature to a minimum EHC convection temperature and generate a third comparison signal,
 wherein the third electronic circuit is configured to select the engine speed maintaining mode when the third comparison signal indicates that the second temperature is less than the minimum EHC convection temperature, and 
 wherein the third electronic circuit is configured to select air pumping mode when the third comparison signal indicates that the second temperature is greater than or equal to the minimum EHC convection temperature. 
 
     
     
       14. A method of operating a catalyst heating system comprising:
 monitoring at least one of (i) a first temperature of a non-electrically heated catalyst (EHC) of a catalyst assembly in an exhaust system of an engine and (ii) an active catalyst volume of the catalyst assembly; 
 selecting an EHC heating mode and generating a mode signal based on the at least one of the first temperature and the active catalyst volume; and 
 controlling current to an EHC of the catalyst assembly based on the mode signal; 
 monitoring a second temperature of the EHC; 
 generating the mode signal based on the second temperature; 
 comparing the second temperature to a maximum EHC convection temperature and generating a second comparison signal; 
 selecting an air pumping mode if the second comparison signal indicates the second temperature being greater than the maximum EHC convection temperature; 
 during the air pumping mode, initiating at least one pumping action to pump air into an inlet of the catalyst assembly; and 
 selecting an engine speed maintaining mode if the second comparison signal indicates that the second temperature is less than or equal to the maximum EHC convection temperature. 
 
     
     
       15. The method of  claim 14 , further comprising, based on the second temperature, selecting an engine speed maintaining mode and an air pumping mode and generating the mode signal,
 wherein the at least one pumping action includes (i) rotating a crankshaft of the engine when the engine is deactivated and (ii) activating an air pump. 
 
     
     
       16. The catalyst heating system of  claim 1 , further comprising a sixth electronic circuit configured to compare the second temperature to a second EHC convection temperature,
 wherein the second electronic circuit is configured to deactivate the air pumping mode when the second temperature is less than the second EHC convection temperature to maintain the second temperature at a temperature greater than or equal to the second EHC convection temperature, and 
 wherein maintaining the second temperature at the temperature greater than or equal to the second EHC convection temperature, maintains the first temperature of the non-EHC at a temperature greater than a catalyst light off temperature. 
 
     
     
       17. The catalyst heating system of  claim 7 , wherein each of the first electronic circuit, the second electronic circuit, the third electronic circuit, the fourth electronic circuit, the fifth electronic circuit, the sixth electronic circuit, the seventh electronic circuit, and the eighth electronic circuit includes at least one of an electronic circuit, an application specific integrated circuit, a processor, memory, and a combinational logic circuit.